Compressible supports for turbine engines

ABSTRACT

A system is provided that includes a first turbine alignment component for a turbine engine; and a shim comprises a metal foam. The shim mounts between a first surface of the first turbine alignment component and a second surface of a second turbine alignment component.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to turbine engines and, morespecifically, to assembly, support, and alignment of components of theturbine engines.

In certain applications, turbines may include various sections designedto be assembled during installation. Each turbine may be encased by aturbine shell and its bearings supported by a “standard” (also referredto as a “pedestal) or exhaust frame. The turbine shells may include armsor other extensions that may be supported by the standard, such asthrough a vertical support on the standard itself. The turbine shellsmay also be vertically supported by legs that attach to ground.

A bearing housing generally covers and protects the bearings of theturbine. During installation, the bearing housing is positioned suchthat the rotor is concentric with the turbine shell to avoidinterference with the other components. Supports on the exhaust framemay engage a support part on the bearing housing to vertically and/orhorizontally align and support the bearing housing. Clearances mayincrease or decrease during operation depending on the support of theexhaust frame and the bearing housing support part. These changes inclearance may introduce uncertainty in the position of the bearingrelative to the stationary components and may result in rubbing orinterference between such components.

The turbine shell generally covers and protects the rotary components ofthe turbine. During installation, the turbine shell is generally alignedwith rotary components to avoid interference with the components.Supports to ground may engage a support part on the turbine shell tovertically and/or horizontally align and support the turbine shell.Achieving desired clearances may be difficult due to thermal expansionof the support part and/or the support of the standards. For example,clearances may increase or decrease during operation depending on theconfiguration of the support of the standard and the support part. Thesechanging clearances may introduce uncertainty in the position of theturbine shell relative to the rotary components and may eventuallyresult in rubbing or interference between such components.

BRIEF DESCRIPTION OF THE INVENTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In a first embodiment, a system includes a turbine engine having aturbine shell, a support assembly configured to support the turbineengine, wherein the support assembly comprises a keyway defined by atleast first and second protrusions, a gib extending from the turbineshell and configured to mate with the keyway and a first shim disposedbetween the gib and one of the first protrusion, wherein the first shimcomprises a metal foam.

In a second embodiment, a system a first turbine alignment component fora turbine engine and a shim comprising a metal foam, wherein the shimmounts between a first surface of the first turbine alignment componentand a second surface of a second turbine alignment component.

In a third embodiment, a system includes a support feature for a turbineengine having a keyway having a bottom, a first side, and a second sideopposite from the first side; a key configured to insert in the keywayand provide lateral alignment of a turbine shell of the turbine engine,and a first shim disposed in the keyway between the key and the firstside, and a second shim disposed between the key and the second side,wherein the first shim and the second shim comprise a metal foam.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic flow diagram of an embodiment of a combined cyclepower generation system having a gas turbine, a steam turbine, and aheat recovery steam generation (HRSG) system;

FIG. 2 is a perspective view of a turbine standard and a turbine shellin accordance with an embodiment of the present invention;

FIG. 3 is a schematic front view of a turbine support feature inaccordance with an embodiment of the present invention;

FIG. 4 is a stress/strain curve of a metal foam in accordance with anembodiment of the present invention;

FIG. 5 is a perspective view of a keyway protrusion of the turbinesupport feature of FIG. 3 in accordance with an embodiment of thepresent invention; and

FIG. 6 is a perspective view of a keyway protrusion of the turbinesupport feature of FIG. 3 in accordance with an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

Embodiments of the present invention include a compliant shim (e.g., ametal foam shim) for aligning turbine components, e.g., turbine shells,of a steam or gas turbine, that are supported on a turbine support,e.g., a standard. The metal foam shim may be installed as a shim betweena keyway of a turbine component and a gib of a turbine support. Duringoperation, the metal foam shim may compress in response to thermalexpansion of the hot turbine component to ensure that the desiredclearances remain between the keyway and the gib. In some embodiments, awear pad, e.g., a stellite wear pad, may be provided between the metalfoam shim and the keyway to support any shear load exerted by the giband/or the keyway. In certain embodiments, the thickness, relativedensity, and material for the metal foam shim may be chosen to ensurethat the metal foam shim provides desired linear elasticity and longoperating life.

FIG. 1 is a schematic flow diagram of an embodiment of a combined cyclepower generation system 10 having a gas turbine 12, a steam turbine 22,and a heat recovery steam generation (HRSG) system 32. System 10 mayemploy one or more support features to align various components in thegas turbine 12, the steam turbine 22, and/or the HRSG 12. As discussedbelow, the support features include one or more compliant shims (e.g.,metal foam shims) to maintain suitable clearances despite thermalexpansion of hot turbine components.

The system 10 may include the gas turbine 12 for driving a first load14. The first load 14 may, for instance, be an electrical generator forproducing electrical power. The gas turbine 12 may include a turbine 16,a combustor or combustion chamber 18, and a compressor 20. The system 10may also include the steam turbine 22 for driving a second load 24. Thesecond load 24 may also be an electrical generator for generatingelectrical power. However, both the first and second loads 14, 24 may beother types of loads capable of being driven by the gas turbine 12 andsteam turbine 22. In addition, although the gas turbine 12 and steamturbine 22 may drive separate loads 14 and 24, as shown in theillustrated embodiment, the gas turbine 12 and steam turbine 22 may alsobe utilized in tandem to drive a single load via a single shaft. In theillustrated embodiment, the steam turbine 22 may include onelow-pressure section 26 (LP ST), one intermediate-pressure section 28(IP ST), and one high-pressure section 30 (HP ST). However, the specificconfiguration of the steam turbine 22, as well as the gas turbine 12,may be implementation-specific and may include any combination ofsections.

Each section of the steam turbine 22, e.g., the low pressure section 26,the intermediate pressure section 28, and the high-pressure section 30,may be generally supported and separated by mid standards 29 (e.g.,pedestals). Similarly, end standards 31 (e.g., pedestals) may begenerally support the ends of the high pressure section 30 and the lowpressure section 26. The standards 29 and 31 may be disposed along theaxis of the turbine 22, and may include various components such assupports, pickups, and piping between the turbine sections 26, 28, and30. As described in detail below, the standards 29 and 31 may alsoprovide for lateral (i.e., horizontal) alignment of the turbine shellsof the sections 26, 28, and 30, though engagement of a gib and keyway.The engagement between the gib and the keyway may be adjusted throughthe use the metal foam shims described herein. It should be appreciatedthat the gas turbine 12 may also include a similar arrangement of one ormore sections and standards, and the gas turbine 12 may also utilize agib, keyway, and metal foam shims for lateral alignment, as discussedbelow.

The system 10 may also include the multi-stage HRSG 32. The componentsof the HRSG 32 in the illustrated embodiment are a simplified depictionof the HRSG 32 and are not intended to be limiting. Rather, theillustrated HRSG 32 is shown to convey the general operation of suchHRSG systems. Heated exhaust gas 34 from the gas turbine 12 may betransported into the HRSG 32 and used to heat steam used to power thesteam turbine 22. Exhaust from the low-pressure section 26 of the steamturbine 22 may be directed into a condenser 36. Condensate from thecondenser 36 may, in turn, be directed into a low-pressure section ofthe HRSG 32 with the aid of a condensate pump 38.

The condensate may then flow through a low-pressure economizer 40(LPECON), a device configured to heat feedwater with gases, which may beused to heat the condensate. From the low-pressure economizer 40, aportion of the condensate may be directed into a low-pressure evaporator42 (LPEVAP) while the rest may be pumped toward an intermediate-pressureeconomizer 44 (IPECON). Steam from the low-pressure evaporator 42 may bereturned to the low-pressure section 26 of the steam turbine 22.Likewise, from the intermediate-pressure economizer 44, a portion of thecondensate may be directed into an intermediate-pressure evaporator 46(IPEVAP) while the rest may be pumped toward a high-pressure economizer48 (HPECON). Steam from the intermediate-pressure evaporator 46 may besent to the intermediate-pressure section 28 of the steam turbine 22.Again, the connections between the economizers, evaporators, and thesteam turbine 22 may vary across implementations as the illustratedembodiment is merely illustrative of the general operation of an HRSGsystem that may employ unique aspects of the present embodiments.

Finally, condensate from the high-pressure economizer 48 may be directedinto a high-pressure evaporator 50 (HPEVAP). Steam exiting thehigh-pressure evaporator 50 may be directed into a primary high-pressuresuperheater 52 and a finishing high-pressure superheater 54, where thesteam is superheated and eventually sent to the high-pressure section 30of the steam turbine 22. Exhaust from the high-pressure section 30 ofthe steam turbine 22 may, in turn, be directed into theintermediate-pressure section 28 of the steam turbine 22. Exhaust fromthe intermediate-pressure section 28 of the steam turbine 22 may bedirected into the low-pressure section 26 of the steam turbine 22.

An inter-stage attemperator 56 may be located in between the primaryhigh-pressure superheater 52 and the finishing high-pressure superheater54. The inter-stage attemperator 56 may allow for more robust control ofthe exhaust temperature of steam from the finishing high-pressuresuperheater 54. Specifically, the inter-stage attemperator 56 may beconfigured to control the temperature of steam exiting the finishinghigh-pressure superheater 54 by injecting cooler feedwater spray intothe superheated steam upstream of the finishing high-pressuresuperheater 54 whenever the exhaust temperature of the steam exiting thefinishing high-pressure superheater 54 exceeds a predetermined value.

In addition, exhaust from the high-pressure section 30 of the steamturbine 22 may be directed into a primary re-heater 58 and a secondaryre-heater 60 where it may be re-heated before being directed into theintermediate-pressure section 28 of the steam turbine 22. The primaryre-heater 58 and secondary re-heater 60 may also be associated with aninter-stage attemperator 62 for controlling the exhaust steamtemperature from the re-heaters. Specifically, the inter-stageattemperator 62 may be configured to control the temperature of steamexiting the secondary re-heater 60 by injecting cooler feedwater sprayinto the superheated steam upstream of the secondary re-heater 60whenever the exhaust temperature of the steam exiting the secondaryre-heater 60 exceeds a predetermined value.

In combined cycle systems such as system 10, hot exhaust gas 34 may flowfrom the gas turbine 12 and pass through the HRSG 32 and may be used togenerate high-pressure, high-temperature steam. The steam produced bythe HRSG 32 may then be passed through the steam turbine 22 for powergeneration. In addition, the produced steam may also be supplied to anyother processes where superheated steam may be used. The gas turbine 12cycle is often referred to as the “topping cycle,” whereas the steamturbine 22 generation cycle is often referred to as the “bottomingcycle.” By combining these two cycles as illustrated in FIG. 1, thecombined cycle power generation system 10 may lead to greaterefficiencies in both cycles. In particular, exhaust heat from thetopping cycle may be captured and used to generate steam for use in thebottoming cycle.

FIG. 2 is a perspective view of a turbine standard 70, e.g., a midstandard 29 or end standard 31, supporting a turbine shell 72, e.g., ashell of the low pressure section 26, the intermediate pressure section28, or the high-pressure section 30. The standard 70 may include anupper half 74 and a lower half 76, and the turbine shell 72 may includean upper half turbine shell 78 or a lower half turbine shell 80. Theturbine shell 72 may be generally supported and aligned by a supportfeature disposed on the standard 70, such as in the region indicated byarrow 79. The support feature may laterally align and support theturbine shell 72 along the x-axis, such as in the directions indicatedby arrows 81, through engagement of a gib and keyway and adjustment ofone or more metal foam shims. As noted above, the gas turbine 12 mayalso use a support feature to laterally align one or shells of the gasturbine with standards in a similar manner.

FIG. 3 is a schematic view of a turbine support feature 82 in accordancewith an embodiment of the present invention. As shown in FIG. 3, theturbine support feature 82 may include a keyway 84 on the standard 70and a protrusion, e.g., gib 86 (also referred to as a “key”), extendingfrom the lower turbine shell half 80. They keyway 84 may be defined byprotrusions 88 extending from the standard 70. The space 83 between theprotrusions 88 may define the keyway 84. In some embodiments, theprotrusions may be machined from the standard 70, welded onto thestandard 70, or manufactured by any suitable technique. The gib 86 isconfigured to mate with the keyway 84 and provide alignment and supportof the turbine shell 72 along the x-axis.

The clearance between the keyway 84 and the gib 86 may be set during“cold” conditions, e.g., when the turbine section is not in operationand is below operating temperatures. For example, some lateral clearancemay be provided between the protrusions of the keyway 84 and the gib 86to prevent damage to the gib 86. During operation, as the turbinesection and the turbine shell 72 heat, the gib 86 may thermally expandinside the keyway 84. To ensure the desired fit between the gib 86 andthe keyway 84, one or more compliant shims (e.g., metal foam shims) 90may be disposed between the gib 86 and each protrusion 88 that definethe keyway 84. For example, as shown in FIG. 3, a first metal foam shim90A may be inserted between one side of the gib 86 and the protrusion88, and a second metal foam shim 90B may be inserted between a secondside of the gib 86 and the protrusion 88. As the turbine shell 70 heatsand the gib 86 grows within the keyway 84, the metal foam shims 90 maybe compressed to maintain the desired clearances between the gib 86 andthe sides of the keyway 84.

As described further below, the metal foam shims 90 may include FeCrAlYfoams, stainless foams, copper foams, Inconel foams, nickel foams,aluminum foams, or any suitable foam, and the thickness, relativedensity, and material for the metal foam may be selected to ensure thatthe metal foam maintains linear elasticity in response to the forcesexerted by the expanding gib 86. Further, the metal foam shims 90 may becompliant enough to prevent damage to the gib 86 and/or the keyway 84during thermal expansion of gib 86, yet retain enough stiffness tomaintain a desired lateral alignment between the gib 86 and the keyway84 and, thus, maintain alignment of the turbine shell 70.Advantageously, the metal foam enables adjustment of the support featurewhen cold to provide easier assembly. Additionally, the metal foam shim90 in the support feature eliminates or minimizes any cold or hotlateral position uncertainty and enables achievement of tighterclearances between static and rotating parts of the turbine.

As mentioned above, the metal foam may be selected to provide thedesired linear elasticity, such as by selecting a metal foam having adesired yield strength or Young's modulus. As will be appreciated, boththe yield strength and the Young's modulus may be a function of therelative density. FIG. 4 depicts a stress/strain curve 94 for anexemplary metal foam, e.g., an FeCrAlY metal foam having a 15% relativedensity. As shown in FIG. 4, the y-axis corresponds to the stress(lbf/in²) of the metal foam for a given strain (in/in) on the x-axis.The linear region 96 corresponds to those portion of the stress/straincurve of the FeCrAlY metal foam that exhibit a linear elasticity. Forexample, in the linear region depicted in FIG. 4, the Young's modulus ofa FeCrAlY metal foam may be approximately 61259 psi. Other regions mayinclude a plateau region 98 in which the stress of the metal foam doesnot change with respect to the strain, and a densification region 99 inwhich the metal foam increases in density and stress rapidly increasesin response to strain.

Thus, when selecting a metal foam for use as a shim in the mannerdescribed above, the metal foam may be selected to ensure that the metalfoam provides linear elasticity up to the strain expected to be inducedin the metal foam shim during operation of the turbine and expansion ofthe turbine shell 70. As mentioned above, the metal foam may includeFeCrAlY foams, stainless foams, copper foams, Inconel foams, nickelfoams, aluminum foams, or any suitable metal foam. Further, the metalfoam may be include open cell metal foams or closed cell metal foams.Additionally, the metal foams used may have a relative density ofgreater than about 5%, such as at least approximately 5%, 10%, 15%, 20%,25%, 30%, 35%, 40%, or greater.

For example, referring to the gib 86 and keyway 84 described above inFIG. 3, for a gib 86 having a width of approximately 6 inches, a heightof approximately 8 inches, and a length of approximately 20 inches, andfor a steady-state gib temperature of 600° F. and 300° F., the stressgenerated in a 15% relative density FeCrAlY metal foam, is about 860 psiand within the linear elastic region 96 depicted in FIG. 4. In addition,for such an embodiment, the total lateral force generated on the metalfoam is 137,600 lbf.

In some embodiments, the metal foam shim 90 may be used with additionalcomponents. FIG. 5 depicts a perspective view of an embodiment of thekeyway protrusion 88 having a wear pad 100 and a keeper plate 102, andFIG. 6 depicts a perspective view of the keyway protrusion 88 withoutthe keeper plate 102. As shown in FIG. 5, the wear pad 100 may absorbsome or all of the shear load, indicated by arrow 104, exerted by thegib 86 on the keyway protrusion 88. As shown in FIG. 6, the wear pad 100may be disposed between the metal foam shim 90 and the gib 86. In someembodiments, the wear pad 100 may be stellite, steel, or any othersuitable material or combination thereof. The keeper plate 102 may beused to retain the metal foam shim 90 and the wear pad 100 in alignmentwith the keyway protrusion 88. For example, the keeper plate 102 mayretain the wear pad 100 against any shear load exerted on the pad in thedirection illustrated by arrow 104. As also shown in FIGS. 5 and 6, thewear pad 100 may be mechanically secured to the metal foam shim 90 byone or more fasteners 106, such as nails, screws, bolts, rivets, or anyother suitable fastener. In other embodiments, the wear pad 100 may bejoined to the metal foam shim 90 with a braze, a weld, an adhesive, orany other suitable process. Thus, in some embodiments, the wear pad 100and metal foam shim 90 may be joined together to form a singlecomponent, while in other embodiments the wear pad 100 may be a separatecomponent from the metal foam shim 90. In other embodiments, the wearpad 100 may be omitted and the metal foam shim 90 may be the onlycomponent disposed between the gib 86 and the keyway protrusion 88.Similarly, the keeper plate 102 may be mechanically secured to thekeyway protrusion 88 by one or more fasteners 108, such as nails,screws, or any other suitable fastener. As also shown in FIG. 6, theprotrusion 88 may include a recess 110 configured to position and/orreceive the shim 90 in a specific area of the protrusion 88. This recess110 may be defined by one or more indentations in or extensions of theinner surface of the protrusion 88. In some embodiments, one or moreprotrusions 88 defining the keyway 84 may include a recess.

It should be appreciated that in other embodiments, the keyway may belocated on the turbine shell 70 and the gib 86 may be located on theturbine standard. In such embodiments, the metal foam shim 90 may beused to provide desired clearances between the gib and keyway in themanner described above. Further, it should be appreciated that thecompliant shims (e.g., metal foam shims) described above may be used inother support features having, for example, a first and second alignmentfeature, male and female alignment features, etc.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

1. A system, comprising: a turbine engine comprising a turbine shell; asupport assembly configured to support the turbine engine, wherein thesupport assembly comprises a keyway defined by at least first and secondprotrusions; a gib extending from the turbine shell and configured tomate with the keyway; and a first shim disposed between the gib and thefirst protrusion, wherein the first shim comprises a metal foam.
 2. Thesystem of claim 1, wherein the metal foam comprises at least one ofFeCrAlY, stainless steel, copper, nickel or aluminum.
 3. The system ofclaim 1, wherein the metal foam comprises a relative density of at leastequal to or greater than approximately 5%.
 4. The system of claim 1,wherein the support assembly reduces or blocks lateral movement of theturbine shell.
 5. The system of claim 1, comprising a second shimdisposed between the gib and the second protrusion, wherein the secondshim comprises the metal foam.
 6. The system of claim 1, wherein thesupport assembly comprises at least one of a bearing, a lubricationsystem, and a rotor, at an end portion of a turbine stage of the turbineengine.
 7. A system, comprising: a first turbine alignment component fora turbine engine; and a shim comprising a metal foam, wherein the shimmounts between a first surface of the first turbine alignment componentand a second surface of a second turbine alignment component.
 8. Thesystem of claim 7, comprising a wear pad, wherein the shim is disposedbetween the first surface and the wear pad.
 9. The system of claim 8,wherein the wear pad comprises stellite or stainless steel.
 10. Thesystem of claim 8 comprising a fastener coupling the wear pad to theshim.
 11. The system of claim 8, comprising a keeper plate configured tohold the shim and the wear pad in position along the first surface. 12.The system of claim 7, wherein the first turbine alignment componentcomprises a protrusion and the second turbine alignment componentcomprises a gib.
 13. The system of claim 7, wherein the first turbinealignment component comprises a gib and the second turbine alignmentcomponent comprises a protrusion.
 14. A system, comprising: a supportfeature for a turbine engine, comprising: a keyway having a bottom, afirst side, and a second side opposite from the first side; a keyconfigured to insert in the keyway and provide lateral alignment of aturbine shell of the turbine engine; and a first shim disposed in thekeyway between the key and the first side, and a second shim disposed inthe keyway between the key and the second side, wherein the first shimand the second shim comprise a metal foam.
 15. The system of claim 14,wherein the first side comprises a first recess configured to receivethe first shim and the second side comprises a second recess configuredto receive the second shim.
 16. The system of claim 15, comprising afirst keeper plate configured to retain the first shim in the firstrecess and a second keeper plate configured to retain the second shim inthe second recess.
 17. The system of claim 15, comprising a first wearpad disposed between the first shim and the key and a second wear paddisposed between the second shim and the key.
 18. The system of claim15, wherein first pad and the second pad are configured to receive shearforces exerted by the key in the keyway.
 19. The system of claim 15,wherein the first pad is coupled to the first shim and the second pad iscoupled to the second shim.
 20. The system of claim 15, wherein themetal foam comprises FeCrAlY, stainless steel, copper, nickel, oraluminum.